This invention pertains to a lightweight door for a horizontal-chamber coke oven. The door has an outer assembly comprising a flexible, thin-walled sealing plate whose perimeter, which carries a sealing edge, is held against the oven frame by means of a flexible pressure distribution frame system to which pressure is applied by the door locking bars, and a lightweight door inner assembly comprising a coking plate that extends into the oven chamber. The coking plate is installed on the inner side of the sealing plate at a distance from it.
The coke oven doors that have been almost exclusively used thus far consist of a heavy casting that can weigh up to 5 tons and more. Such coke oven doors, which as a rule are equipped on the inner side with a ceramic plug approximately 16 inches, i.e. 40.6 centimeters, deep, may weigh between about 750-800 kilograms per meter, are difficult to handle, and require large and complicated machines to handle them. Furthermore, such doors are normally equipped with edge seals that, sooner or later, are unable to bridge the gaps that are created between the seals and the oven door frames or jambs, due to the thermal cycling that occurs during coke oven operation. These gaps permit emissions to escape from the ovens. Such a door is shown in U.S. Pat. No. 4,261,797, Kelly.
In July 1975 Battelle Columbus Laboratories published Report No. EPA-650/2-75-064 that described the results of a project undertaken for the National Environmental Research Center to analyze various known methods for sealing coke oven doors then in use. The report, entitled "Study of Concepts For Minimizing Emissions From Coke-Oven Door Seals", stated that the fundamental cause of visible emissions from coke oven seals is "+++the continuing thermal warpage and distorting of the cast-iron, oven-mounted jambs. While there are also design and warpage problems in existing door mounted seals, the degree of warpage on many jambs is in excess of the limits that some existing seals have been designed to handle." Unfortunately, the report offered no answers for the coke oven door seal problems.
Subsequently, there have been granted a number of patents directed to coke oven doors having improved designs for dealing with door sealing problems; see U.S. Pat. No. 4,145,258, Masamitsu, and U.S. Pat. No. 4,293,389, Clement. Also there are a number of patents directed to lightweight coke oven doors, see U.S. Pat. No. 4,119,496, Campana, and West German Patent No. 31 38 406.4. The latter patent describes a lightweight coke oven door that is easy to handle and one that can be positioned more accurately in front of a coke oven. The door body itself is connected with the chamber frame or pressed against it at more than two points. The known door consists of a sealing plate, which represents the actual door body and has knife edges at its periphery, which knife edges are pressed against the chamber frame by means of pressure elements, whereby these pressure elements bear against a continuous sealing frame made from a U-channel or from a similar shape and against the locking bars distributed over the height. In order to insure a uniform distribution of the bearing forces, six or more such locking bars are provided. Such a coke oven door is light in weight and highly flexible, because the door body, as it is described, consists of only a thin-walled sealing plate. Therefore it easily fits to the existing shape of the oven frame. As is known, owing to the temperature effect, the oven frame and the door warp away from their positions, whereby leaks can occur, since the knife edge cannot be continuously pressed sufficiently tightly against the oven frame during the thermal cycling of the ovens. As stated, this is not the case with the known flexible doors having the sealing plate as the door body. The flexibility of the one-piece door body is further increased, and thereby its weight is reduced, by eliminating the ceramic plug on the inner side and instead providing a coking plate supported by spacers at a distance from the door body. It has been found that after long use, owing to the accumulation of dirt or other deleterious effects, the knife edge is no longer pressed uniformly by the pressure element. This pressure element, preferably an inflatable tube, must also be protected against relatively high temperatures and thus it represents a weak point of the entire door. Also, installation of locking bars over the height of the coke oven door is frequently complicated, particularly when existing coke ovens are to be retrofitted with the described door. It is of a further disadvantage that, owing to the use of the sealing frame, which resists bending and runs along the periphery of the door and which bears against the pressure element, such doors have an element that reduces flexibility and also increases the door weight.
Accordingly, it is an object of the invention to provide a flexible coke oven door that insures a sure and reliable fit of the door sealing plate to the oven frame even at high temperatures and after long service.
A further object of the invention is to provide a self-sealing lightweight flexible coke oven door that is compatible with existing door handling and oven working machinery and capable of being retrofitted to existing and future coke ovens of all oven heights and design.
Another object is to provide a self-adjusting lightweight flexible coke oven door that maintains the door sealing edge in contact with the surface of the door jamb as the jamb is caused to warp and distort by the thermal cycling that occurs during both short and extended periods of coke oven operation.